Well, I am certainly the furthest thing from the authority on DIY subs.
But, in a ~1400 cubic foot room, I can guarantee he will not need much power to reach reference levels. That is, if his room is really only 1400 cubes and does not open to other adjoining rooms.
There is no question that better amps DO make a difference. But, how much difference in a tiny room like that is very debatable. And yes, in this application and certainly in mine the LMS is much more than needed by leaps and bounds. Hell realistically, two SVS PB-10s were more than enough...
But, my theory is it is easier to change out amps than drivers, so why not start a project with the best driver you can afford and worry about the other details later?
As you probably know I am currently using a BKA @1 ohm feeding ~2000-3000 watts, no one really knows what it yeilds in reality, probably less, maybe more??
I tried one BKA on each coil @ 2 ohms, 1 BKA for both coils @ 4 ohm. The only slighly perceptible difference in running the BKA at 1 ohm, as in more power to the LMS, is a stronger bottom end, say below 20 Hz. With only a 6db boost applied at 20Hz it really doesn't take much more than a 1000-1500 watts to yield painful output. Below that I prefer shakers anyway.
Plus, in a room that small you can hear fans on amps, even if modded. That is why I wanted to at least give the BKA a shot for sub duty. Of course, that won't be a problem on most movies, but during quieter segments I did not want to hear any fans.
After all, how loud can you really listen?
If I can hit around 116-119 db on movie passages in my ~1700 cube room with 1000 watts, three thousand more in my mind is just not necessary.
Sure, I guess the LMS could handle 5 Kw of power but unless you are into making basspig style videos with walls buckling, heads exploding and things
, then it is all just somewhat pointless for everyday listening purposes. There is nothing wrong with carnage subwoofer style, but that is just not what my intentions are/were.
It might be worth it to try an EP2500 if you can. Even if you only get 1500 real world watts at 4 ohms (despite being rated @ 2400), I will guarantee you will be more than satisfied with the results. Hell you can probably score a used Ep for